Editor's Note: Scientific American's George Musser will be chronicling his experiences installing solar panels in Solar at Home (formerly 60-Second Solar). Read his introduction here and see all posts here.

Earlier this week I posed the question of whether old houses will ever be able to reduce their energy needs by the factor of five or so needed to combat climate change. My discussion was inspired, in part, by a provocative essay written last year by preservationist Sally Zimmerman of Historic New England. Yesterday she wrote to say that my post and the comments that people left have been widely circulated among preservationists. She offered some more thoughts that I think frame the issue beautifully:

Here in New England, where we depend heavily on oil heat and where old houses constitute a large component of our housing stock, we have to deal head-on with the seeming contradictions of conserving energy and preserving historic architecture. But does this mean these two goals are in conflict? Maybe not, if preservationists and conservationists can find a way to meet each other halfway. From the preservation perspective, here are some thoughts on where we are coming from.

  1. Old houses are not the problem: We can't solve the energy crisis on the backs of our "old" houses. According to the U.S. Census Bureau, just over 8% of the nation's existing housing units were built before 1920. Perhaps making the nation's "new" houses more energy efficient should be called the "92 percent solution."
  2. Early adopters of new technologies pay a higher price: Innovative gadgets usually need some shelf time to bring the cost down and work the bugs out. We should bear this in mind with cutting-edge green technologies and materials and keep them out of our old houses until we know they are safe and effective. "Really old" houses (such as houses built more than 150 years ago) really aren't the place to experiment with the newest technologies: they're just too rare and important to be subjected to an onslaught of the most innovative energy strategies. Considering the age and significance of a house will help balance historic preservation and energy efficiency goals.
  3. Go ahead and pick the low-hanging fruit: By all means, do everything you can to make your old house less energy consumptive with retrofits that are easily achieved and don't damage or destroy historic fabric: blower door tests; air sealing; insulating attic floors, basement ceilings, pipes and ducts; weather-stripping and adding storm windows and doors; and keeping heating and cooling equipment serviced. New England preservation and energy groups have already teamed on a new guide outlining prudent strategies. And Historic New England, with 36 house museums, plans to retrofit the 1793 Lyman Estate for a 50 percent reduction in energy use with comprehensive, but reversible, interventions.
  4. Keep it simple: Sophisticated "deep energy retrofits" that include super-insulation of exterior walls, roofs, and foundations yield dramatic reductions in energy consumption but may have too many "moving parts" for an old house whose "parts" have very likely moved, shifted, settled, sagged, and generally been mucked-around with a lot already. The USGBC and the American Society of Interior Designers offer good information on the scope of the deep energy retrofit but preservationists will argue that this solution is better suited to newer houses (see the "92 percent solution," above).
  5. Get with the program: Energy interventions are a critical part of the solution to a global threat. Recently, the Advisory Council on Historic Preservation issued a prototype programmatic agreement with the Department of Energy providing guidance for preservation regulators around the country to approve energy retrofits that don't damage significant fabric or publicly visible aspects of historic properties. Old houses have adapted to new technologies before and they can do it again as long as those of us who love old houses and our green planet approach energy interventions with common sense and an open mind.

Energy audit at Lyman Estate. Courtesy of Historic New England